Kinect Sports Season Two
70 Achievements
1,500
60-80h
Xbox 360
Maximum Velocity
Held the tuck position for at least 10 seconds when playing Skiing
20
How to unlock the Maximum Velocity achievement in Kinect Sports Season Two - Definitive Guide
When going down hill, just crouch down with your hands to the side and hold it for 10 seconds. You do not need to worry about the flags. Very easy!
Pretty much as described, just bend over and keep your legs and arms together to gain speed. You’re free to do some leaning while tucked.